The Obama administration wants to rebuild the national
electric grid that delivers power to everyone's toasters
and televisions. One reason is that the grid can't
handle all the new solar and wind power the president
wants to build to create a greener energy economy.

Here's the problem: Solar and wind power are intermittent.
Sometimes it's sunny, sometimes it's not, and it's
the same for wind. But the grid needs constant and
reliable sources of power. What's the answer? One
solution, says Imre Gyuk, a researcher at the Department
of Energy, is to store that energy. Gyuk and engineers
at power companies have an idea for how to do that.

"You put a large number of small batteries around
a neighborhood," Gyuk says, "just like the neighborhood
transformers — just a little green box that's innocuous."

By small, he means about the size of the battery
in a hybrid car, and it would be hooked up to the
grid. In fact, DOE and American Electric Power, a
large utility, plan to use batteries made for hybrid
plug-in vehicles to create such a constellation of
storage sites. The batteries are charged when there's
surplus power — say, on an especially windy day —and
then tapped on a cloudy or windless day.

"If you have these storage units sitting throughout
the community, then you can simply withdraw half an
hour's worth of storage to make up for the wind,"
Gyuk says.

The Department of Energy is plowing more than $600
million from the government's stimulus package into
storage technologies. Another possible solution is
something called a "flywheel" — a spinning metal rotor,
floating in a vacuum inside a steel cylinder.

Gene Hunt, communications director at Beacon
Power in Massachusetts, says one of the company's
flywheels spins at 16,000 revolutions per minute.

"It's the same principle as that of a potter's wheel,"
he says. "The potter's wheel is powered by the human
foot, pumping the pedal up and down. It turns this
wheel which has a certain weight, it brings it up
to a speed, and when you take your foot away, it continues
to spin. It's using the energy that's stored in there."

A small amount of electricity is needed to keep the
flywheels spinning, and the machines store that power
as rotational energy. Beacon is building flywheel
"farms" that can return that energy as electricity
in short bursts when operators need to meet a spike
in demand on the grid.

Sharing Power

There are other ways to store electricity for the
grid: Water can be pumped up into an elevated reservoir
when electricity demand is low (and electricity production
is in excess); then it can be released to flow through
turbine generators to make more electricity when demand
is high.

But all these devices need software to keep them
linked to the grid. That's something a company called
GridPoint does. Karl Lewis, the company's chief strategy
officer, says the idea is to allow utilities to draw
on electricity in household storage devices when customers
don't need it, much like a virtual power plant.

That "shared" power could extend to electric cars.
As the car wanders around the grid, Lewis says, "we
know where the car is, where it's plugged in, how
much energy it needs. And what happens is that the
car becomes a smart charging asset available both
to the consumer and the utility."

Lewis acknowledges that some people may not want
the utility to know where they are all the time. He
says people would have the choice to participate in
a program like this. But, he adds, hooking up to the
new grid as an energy partner may ultimately mean
cheaper utility bills, and more wind and solar electrons
running Americans' appliances or cars.